MEXICO CITY (AP) — The Mexican army acknowledged for the first time Friday that some of its soldiers have been killed by bomb-dropping drones operated by drug cartels.

Defense Secretary Gen. Luis Cresencio Sandoval did not provide exact figures on the number of casualties suffered in the attacks, almost all of which occurred in the western state of Michoacan.

“Our personnel have suffered wounds, and some of our troops have even died” in the attacks, Sandoval said. The army had previously acknowledged that soldiers had been wounded in Michoacan by improvised explosive devices, or IEDs.

Sandoval did not say when the attacks took place, but suggested they targeted patrol units. He said the army was acquiring anti-drone systems to combat the threat.

“What we are seeking with this anti-drone equipment is to have the security capability, which we lack, for our personnel performing reconnaissance and patrols,” Sandoval said.

Sandoval said the army continues to encounter far more road-side bombs than drone-dropped ones.

The Jalisco drug cartel has been fighting local gangs for control of Michoacan for years, and the situation has become so militarized that the warring cartels use roadside bombs or IEDs, trenches, pillboxes, home-made armored vehicles and sniper rifles.

The cartels — especially the Jalisco cartel — have frequently equipped larger commercial drones with specially-built mechanisms to release small but fairly professional-looking aerial bombs. Last year, authorities found a machine shop used to make metal bomb casings for such attacks.

In the only previous detailed report on cartel bomb attacks in August 2023, the defense department said at that time a total of 42 soldiers, police and suspects were wounded by IEDs in the first seven and a half months of 2023, up from 16 in all of 2022.

That same year, one National Guard officer and four state police officers were killed in two separate car-bomb attacks.

Drone-carried bombs, which were unknown in Mexico prior to 2020, rose to at least 260 in 2023, but even that number may be an underestimate. Residents in some parts of Michoacan say that attacks by bomb-dropping drones are a near-daily occurrence.

Also Friday, Mexico’s Navy acknowledged that two military helicopter crew members died earlier this year when their chopper went down in the Pacific ocean while chasing cocaine-smuggling boats. Officials said the U.S. Navy had agreed to help in recovering the sunken helicopter and the crew members’ remains.